Here are the corrections for each of the questions in your exercise:

9. Most students in my class are hard-working. They **always** finish all their homework before they come to class.
- Correct Answer: **B. always**

10. Having **some** vehicles on the streets causes pollution in the city.
- Correct Answer: **A. some**

11. My sister seldom plays badminton after work; she prefers **to swim** in the nearby river.
- Correct Answer: **B. to swim**

12. There weren’t **enough** chairs in the room, so some of us had to stand.
- Correct Answer: **C. enough**

13. I can't sleep - there is too **much** noise in the neighborhood at night!
- Correct Answer: **B. too much**

14. When I was younger, I usually played spinning tops with my brother.
- Correct Answer: **C. usually** (correct as it is)

15. We’d like to announce **that** the village festival will take place on January 21st to February 2nd.
- Correct Answer: **C. that** (insert 'that' for clarity)

16. All the children are interested in the animal **performance** at the festival.
- Correct Answer: **B. performance** (correct as it is)

If you have any further questions or need additional help, feel free to ask!